# Trimester Seminar

## Venue: HIM, Poppelsdorfer Allee 45, Lecture Hall

## Friday, January 12^{th}, 14:30

**What is... an associator?**

### Leila Schneps (Institut de Mathématiques de Jussieu)

## Friday, January 12^{th}, 11:00

**What is... relative completion?**

### Richard Hain (Duke University)

## Thursday, January 11^{th}, 11:00

**What is… a motivic Galois group?**

### Yves André (Institut de Mathématiques de Jussieu)

## Tuesday, January 9^{th}, 18:00

**Special Laurent polynomials and Apery numbers via normal functions**

### Matthew Kerr (Washington University in St. Louis)

## Tuesday, January 9^{th}, 16:30

**Introduction to mirror symmetry: special Laurent polynomials**

### Vasily Golyshev (National Research University Higher School of Economics (HSE))

## Monday, January 8^{th}, 18:00

**Introduction to mirror symmetry: generic Laurent polynomials**

### Hiroshi Iritani (Kyoto University)

## Monday, January 8^{th}, 16:30

**Introduction to mirror symmetry: four geographies**

### Vasily Golyshev (National Research University Higher School of Economics (HSE))

## Monday, January, 8th, 15:00

**Introductory Words and Talks**

### Christoph Thiele (HIM), Don Zagier (MPIM) and Spencer Bloch (The University of Chicago/MPIM)

## Friday, January, 5^{th}, 14:00

**Modular arrangements**

### Andrey Levin (LMS NRU HSE)

Lecture notes I Lecture notes II

Abstract

I want to present a potential source of periods of geometrical origin which can be interesting for number theory. The square X^{2} of the modular curve X=H/SL_{2}(Z) is naturally equipped with a collection of curves, the so-called modular correspondences. A finite set of these curves is called a modular arrangement. A pair of arrangements in generic position determines some period, corresponding to the cohomology group of the complement of the first arrangement modulo the second.